Gloves are commonly used to protect hands in an industrial or household environment. These commonly used household or industrial protective gloves do not resist oil and are not commonly cut resistant. The gloves that may be used in tar sand or oil shale environments need to meet specific codes that require the gloves to be fire resistant. As an example, the national standard of Canada code CAN/CGSB-155.20-2000 details tests for workwear for protection against hydrocarbon flash fire. The code has three classes, type 1 covering single layer garments, type 2 covering multilayer garment and type 3 covering disposable garment.
Certain cut resistant fibers, knitted liners, coated gloves are known in the prior art. Fibers including steel fibers, fiberglass, para-aramid fibers (Kevlar®) and extended chain gel spun polyethylene fibers (Spectra®) are well known in the art. Of these fibers, generally only steel fibers, glass fibers and para-aramid fibers meet the Canada code CAN/CGSB-155.20-2000. Extended chain polyethylene Spectra® is not generally considered flame retardant due to the ability of a polyethylene fiber to catch fire. Non-cut resistant fibers that are typically used to wrap cut resistant fibers as disclosed in the prior art also have problems in meeting the Canada code CAN/CGSB-155.20-2000 fire resistance code. Polycotton and nylon 6 wrap fibers readily catch fire when exposed to a flame. However, polyester fibers char readily and prevent the propagation of the flame front. Nylon 6,6 also self-extinguishes a flame readily.
Generally, cut resistant liners are fabricated from cut resistant yarns. Cut resistant liners of the prior art typically contain steel fibers, glass fibers, para-aramid fibers (Kevlar®), gel spun extended chain polyethylene fibers (Spectra®). These yarns are constructed from one or more of these cut resistant fibers and may be twisted or wrapped with cotton, polyester, nylon and the like. For example, U.S. Pat. Nos. 4,777,789 and 4,838,017 to Kolmes et al. disclose cut resistant yarns with a wire core wrapped with nylon, aramid, extended chain polyethylene, cotton, wool, fiberglass, polyester, polycotton, asbestos. The wrappings of cotton, nylon, polyethylene will catch fire when exposed to flame. Further, these wrapped, cut resistant yarns with a wire in the core are subject to shorting electrical circuits. U.S. Pat. No. 4,651,514 to Collett discloses electrically nonconductive, abrasion and cut resistant yarns. This electrically non-conductive, cut and abrasion resistant yarn is for use in the manufacture of protective coverings and includes a core of monofilament nylon having a diameter in the range of about 0.004 to 0.020 inches, a first wrap on the core of at least one strand of aramid fiber and a second wrap on the core of texturized nylon of two to eight ply construction. Since the yarn contains nylon monofilament yarn and textured nylon, it is not hydrocarbon flash fire resistant. U.S. Pat. Nos. 4,936,085 and 5,177,948 to Kolmes et al. disclose non metallic cut resistant yarns with a core that contains a fiberglass strand that is tightly wrapped with relatively large denier fiber strands in two layers wound in opposite directions so as to entirely cover the fiberglass containing inner core. As indicated in U.S. Pat. No. 5,177,948 the spacing between fibers in the wrapped fibers is small due to the large number of turns of wrappings used which is in the range of 8 to 12 turns per inch. The denier of the composite yarn produced is about 3500 in U.S. Pat. No. 4,936,085 and 2000 to 5000 in U.S. Pat. No. 5,177,948. Such yarns cannot be tightly knitted and produce thick knitted liners. If latex dipped gloves were made therefrom, they would not flexible. Use of polycotton nylon wrapping disqualifies these fibers for hydrocarbon flash fire applications. U.S. Pat. Nos. 5,628,172; 5,644,907 and 5,655,358; to Kolmes et al. disclose cut resistant yarns that are wrapped. These composite yarns contain extended chain polyethylene and polycotton, both components capable of being ignited and therefore are unsuited for hydrocarbon flash fire application. Some of the yarns contain metallic cut resistant fibers, which can short circuit electrical circuits. U.S. Pat. No. 5,845,476 to Kolmes discloses composite yarn with fiberglass core. The core of the composite yarn comprises one or more fiberglass strands that are wrapped with a sheath strand and a cover strand at a rate of 8 to 12 turns wound in opposite directions. The sheath strand and cover strand are made from extended chain polyethylene, aramid, nylon, and polyester, and due to the tight wrappings of a large denier sheath and cover strands the overall diameter of the composite yarn is large with a denier in the range of 1800 to 5000 even though the untwisted parallel fiberglass strands only have a total denier of 200 to 600, which means that the sheath strand and cover strand that completely cover the fiberglass strands and substantially add to the diameter of the composite yarn. This composite yarn is said to go through knitting machine needles without breakage of the fiberglass core, but due to its large denier only thick knitted liners with low stitch density per inch can be produced. When this knitted liner is dipped in latex, it only produces thick gloves with limited flexibility. U.S. Pat. Nos. 6,341,483 and 6,349,531 to Kolmes et al. disclose a multi-component yarn that has a non-metallic cut resistant core which may be extended chain polyethylene or aramid fiber air interlaced with polyester, nylon, acetate, rayon, and cotton. Fiberglass may be used as a third covering also air interlaced. Use of flammable fiber components such as polyethylene, nylon, acetate, rayon and cotton disqualifies this multi-component yarn as a hydrocarbon flash fire resistant garment. Wire-containing cut resistant fibers are disclosed in U.S. Pat. Nos. 6,363,703; 6,381,940; and 6,467,251, U.S. Patent Application Publication No. 2005/0086924 to Kolmes et al. disclose use of a wire in the cut resistant fiber and are therefore unsuited for electrical short prevention applications. In addition, these fibers contain flammable fibers including polyethylene fibers, cotton, nylon and the like and will not meet the hydrocarbon flash fire resistance requirements. U.S. Pat. No. 6,701,703 to Patrick discloses high performance yarns and method of manufacture. The yarn has a core with glass fibers that are stress-cracked and a metal fiber which is wrapped by a sheath of aramids, acrylics, melamines, modacrylics, polyesters, polypropylenes, nylons, cellulosics, silica, graphites, carbon fibers, high density polyethylene, polyamides, metals, polybenzimidazole, co-polymers. The sheath is not hydrocarbon flash fire resistant. U.S. Pat. No. 7,111,445 to Threlkeld et al. discloses a fire-resistant sewing yarn and the products made therefrom. This sewing yarn has a central core of elongatable fiber which is nylon or polyester, wrapped by fiberglass and the outer cover is nylon and polyester. Wrapping with fiberglass requires the fiberglass denier to be very small and therefore does not have cut resistance. The sewing yarn is intended to hold together after exposure to 1000° C. after a fire, when everything bums out except fiberglass portion of the sewing yarn. U.S. Pat. No. 7,143,570 to Piat discloses thread having properties of resistance to cutting. This thread consists of a core thread sheathed with a continuous filament. The core is a plurality of glass filaments and is wrapped by a continuous filament selected from polyamide, polyester, acrylic, cotton, polyethylene, polypropylene, and meta- and para-aramid. Since non-flame resistant fibers are possible in this thread, the thread may not be hydrocarbon flash fire resistant. Moreover, use of filaments of glass fibers does not provide high level of cut resistance. In U.S. Pat. No. 7,469,526 (Patrick), a heat and flame resistant sewing thread uses a core of glass filaments having an elongation of less than about four percent having a sheath of microdenier aramid fibers ring spun about the core. The ring spinning introduces twists in the fiberglass core while the ring spun aramid fibers have an opposite twist. When tension is applied to this composite thread, it elongates to about four percent due to the relaxation of twists in the fiberglass core and the ring spun aramid fibers. This composite is for use as a sewing thread and is unsuitable for use in a knitting machine since the ring spun aramid fibers surrounding the core could be readily stripped off.
U.S. Pat. No. 5,070,540 to Betcher discloses a protective garment. The protective garment has a knitted liner with stainless steel wires together with a synthetic non-aramid nylon fiber wrapped with two wraps of polyester fiber. The knitted liner is coated with a liquid impervious polymeric coating selected from natural latex, polyacrylates e.g. polyethyl acrylate, polybutadiene, styrene-butadiene copolymer, acrylonitrile-butadiene rubber and neoprene (polychloroprene). Since the core has a nylon fiber, and the polymeric coating may have non flame resistant polymers, the protective garment may not meet hydrocarbon flash fire resistance requirements. In addition, the presence of steel fiber will lead to short circuit of electrical circuits.
U.S. Pat. No. 5,822,791 to Baris discloses protective material and method. The base layer of the protective article has cut resistant fibers, which is joined to an intermediate layer of natural fibers joined in one or more locations. The intermediate layer is covered with a liquid impervious elastomeric layer, which never contacts the cut resistant base layer. The base layer may be a knitted liner with steel fiber or cut resistant liquid crystal polymer fiber wrapped with polyamide or polyester fiber. The elastomeric layer is indicated to be acrylonitrile rubber, acrylonitrile butadiene rubber, nitrile butadiene rubber, nitrile silicone rubber, polychloroprene, polyvinyl chloride, polyisoprene, Nomex or Viton. Since the cut resistant knitted liner has polyamide (nylon 6) and the intermediate layer has natural fibers, the protective material does not resist hydrocarbon flash flame.
U.S. Pat. No. 6,021,524 to Wu et al. discloses cut resistant polymeric films. The polymeric matrix of the film comprises a plurality of cut resistant fibers in a middle layer and is indicated to be usable for medical or industrial gloves. The middle layer is not a knitted liner and contains a three-dimensional network of chopped fibers of glass fibers, steel fibers, aramid fibers and particle filled fibers. The polymeric matrix is made from natural rubber, polychloroprene, styrene-isoprene-styrene block copolymers, styrene-ethylene butylene-styrene block copolymers, styrene-butadiene-styrene block copolymers, polyurethane, polyurea, nitrile rubber, vinyl chloride based polymers. Not all of these chopped fibers or polymeric matrices disclosed will pass the hydrocarbon flash fire resistance test. U.S. Pat. Nos. 6,075,081; 6,347,409; and 6,352,666 to Nile et al. disclose manufacture of rubber articles. Polychloroprene latex rubber articles made from a polychloroprene aqueous latex and being coated with a polypropylene wax emulsion are provided. The rubber article does not have a knitted liner and therefore is not a cut resistant latex article.
When the latex layer used is made porous in order to provide breathability, the resulting thickness of the porous latex layer is generally greater resulting in an awkward feeling glove with limited touch sensitivity. For equivalent wear resistance, the foam layer must be thicker than a non-foamed layer. A number of prior art patents address gloves and their forming methods using a relatively thick knitted liner and a thick coating of latex layers. The combination of a thick knitted liner and a thick foamed latex layer do not result in a small overall glove thickness and the glove product does not provide flexibility and easy mobility of fingers and hand.
The knitting technology of V flat bed machines have improved significantly in the past few years. Knitting needles in the knitting machine were essentially a hook with a swingable latch that captures a yarn that is being knitted, but this knitted loop cannot be held or transferred back or combined with a previously knitted loop. U.S. Pat. No. 6,915,667 to Morita, et al. discloses a composite needle of knitting machine. This composite needle comprises a needle body having at a tip end a hook, a slider formed by superposing two blades, wherein the composite needle of the knitting machine is formed such that a blade groove provided in the needle body supports the blades of the slider when the needle body and the slider can separately slide in forward and backward directions. This slider acts as a latch securing the yarn being knitted and can transfer the yarn loop for pushing the loop backwards, holding the loop or transfer back to a previously knitted loop providing automatic knitting of complex patterns as detailed in the Shima Seiki web page http://www.shinaseiki.co.jp/product_knite/knite.html. This type of composite needle is available in Shima Seiki commercially available whole garment knitting machines SWG021 and SWG-FIRST machines. The SWG-FIRST machines provides gaugeless knitting, meaning that the number of needles may be changed on the fly under computer control seamlessly by using split stitch technology, as detailed in U.S. Pat. No. 7,207,194 to Miyamoto entitled “Weft knitting machine with movable yarn guide member.” These machines are ideally suited for changing the reinforcement geometry of the knitted location at specific locations of the liner. A knitting needle size needs to be selected according to the denier size of a yarn and correspondingly, a knit pattern is generated in a standard knitting machine. For example, a 10 gauge needle produces typically 10 knits per inch.
Accordingly, there is a need in the art for composite yarn that has fire resistant materials that has a relatively low denier and is capable of being used in a commercial knitting machine without damage to a fiberglass containing core of the composite yarn even when the composite yarn is passed through knitting machine needles at high speed. The smaller overall diameter of the composite yarn will result in flexible cut resistant knitted liner. Accordingly, there is a need in the art for a flexible glove that has hydrocarbon flash fire resistant yarns in a cut resistant liner and is coated with a hydrocarbon flash fire resistant liquid impervious polymer for use in petroleum oil-environment. The cut resistance is required since handling sharp objects with a slippery oil film on a glove results in tool slippage and can result in cuts and bruises. The oil contamination contaminates the wound and prevents rapid healing of the wound. Moreover, the cut resistant liner may not contain steel fibers or electrically conductive material such as carbon fibers especially when electrical circuits are present. These electrically conductive fibers may heat rapidly creating a burn and may even initiate a fire and at the same time short circuit electrical components.